Cryogenic Equipment

J. G. Weisend II

www.europeanspallationsource.seJune 2019

Goals

• Describe the nature, performance and design considerations of various components found in cryogenics

– Transfer Lines

– Connections• Bayonets

• Flanges

– Valves

June 2019 Lecture 17 Cryogenic Equipment Slide 2

Transfer Lines

• Vital part of a cryogenic system

– Transfers cryogenic fluids between components

– Essentially a long cryostat

– Can be a significant part of system cost and heat leak

– Can be acquired commercially or custom built

• Key design issues

– Thermal contraction (significant due to long lengths)

– Heat Leak (use of active thermal shields)

– Forces generated by fluid pressure, thermal contraction must be managed so as to not impact alignment of components

– Vacuum integrity (pump outs and relief valves)June 2019 Lecture 17 Cryogenic Equipment Slide 3

Transfer Line ExampleITER

June 2019 Lecture 17 Cryogenic Equipment Slide 4

“Design, Analysis and Test Concept for Prototype

Cryoline of ITER”B. Sarkar et. Al

Adv. Cryo. Engr. Vol 53 (2008)

Transfer Lines

▪ Methods to address thermal contraction

• Rigidly fix interior pipes to vacuum shell and install bellows on vacuum shell and on all pipes

• Install bellows on cold pipes only

• Use bends to allow interior pipes to contract

• Use Invar pipes to reduce amount of thermal contraction (CERN/LHC)

June 2019 Lecture 17 Cryogenic Equipment Slide 5

“The Local Helium Compound Transfer lines For The Large Hadron ColliderCryogenic System”C. Parente et al. Adv. Cryo Engr. Vol 51 (2006)

June 2019 Lecture 17 Cryogenic Equipment Slide 6

Transfer Lines Become ComplicatedDistribution Systems

ITER Cryogenic Distribution System

June 2019 Lecture 17 Cryogenic Equipment 7

Transfer Lines Become ComplicatedDistribution Systems ESS Cryogenic Distribution System

Cryoline vacuum

jacket (DN550)

Valve box

vacuum jacketCryoline

supportBottom plate

(demountable)

Cryoline

interconnection

sleeve with axial

compensator

(DN600)

Interconnection

sleeve at the

interface to the

cryomodule

Jumper connection vacuum jacketwith a lateral compensators

(vertical: DN350 horizontal: DN450 )

Valve box

supports 8

Integration Tunnel CMs – CDS(Sliding Sleeve Closed)

9June 2018Large Scale He Cryogenics J. G. Weisend II

CryoOps 2018

ESS Cryogenic Distribution SystemUnder Installation

June 2019 Lecture 17 Cryogenic Equipment 10

Transfer Lines

• In some cases, commercially produced transfer lines are the solution

• Nexans flexible, multiple flow transfer line

June 2019 Lecture 17 Cryogenic Equipment Slide 11

Bayonets

• Demountable piping joints that allow quick connections of cryogenic lines

• Very useful in connecting to replaceable cryogenic liquid supplies. Frequently used in “U-Tubes”

• Reentrant, low heat leak design

• Uses at least one 300 K gas seal and sometimes a cryogenic liquid seal (typically Teflon)

• Must be built to tight mechanical tolerances

• Receiving end must be lower or at least horizontal to delivery end to avoid convection

June 2019 Lecture 17 Cryogenic Equipment Slide 12

PBA Series Bayonet from PHPK Technologies

June 2019 Lecture 17 Cryogenic Equipment Slide 13

Note:

No liquid seal

Very tight tolerances between

male & female sides to minimize convection

Long, thin walls connect 300 K and 4.2 K

Air Force Style Hydrogen Bayonetfrom “Cryogenic Equipment” – D. Daney Handbook of Cryogenic Engineering

June 2019 Lecture 17 Cryogenic Equipment Slide 14

FNAL/SMTF Bayonet Can

June 2019 Lecture 17 Cryogenic Equipment Slide 15

SNS Refrigeration Plant showing U-tubes

June 2019 Lecture 17 Cryogenic Equipment Slide 16

Flange Connections

• How else do we connect pipes at cryogenic temperatures?– Welding is almost always the most reliable approach but sometimes a

demountable joint is required.

• There are a number of demountable flange options– Anything involving a polymer or rubber O-ring will clearly not work at

cryogenic temperatures– Sealing options include

• Flanges using a soft metal gasket ( typically copper) such as Conflat flanges• Flanges using a metal “c” ring• Flanges using an indium o-ring – best used in test scenarios and typically

home-made

– With proper design and installation all of these approaches can provide leak tight joints down even at superfluid helium temperatures (< 2.2 K)

• Note that vacuum and liquid leaks are a major source of problems in cryogenics. Carefully thought out and reliable connections are a key to success

June 2019 Lecture 17 Cryogenic Equipment Slide 17

Examples of Flanged Connections for Cryogenic Use (both are commercially available)

June 2019 Lecture 17 Cryogenic Equipment Slide 18

ConFlat Style

Soft Metal GasketC Ring Style

Example of Indium O-Ring Seal

June 2019 Lecture 17 Cryogenic Equipment Slide 19

From G. McIntosh in

The Handbook of Cryogenic Engineering

Use of Invar Washers

• If upon cool down the flange material shrinks more than the bolt material then the seal may open up and leak

• One way to prevent this is to use invar washers so that the seal actually tightens during cool down

• The goal here is to size the components such that the bolt shrinks more than the combination of the 2 flanges and the invar washer

June 2019 Lecture 17 Cryogenic Equipment Slide 20

Valves

• Valves are an important part of cryogenic systems

• Valves direct flows and control both flow rates and pressure drops

• Cryogenic valves have to operate at cryogenic temperatures and minimize the heat leak from room temperature

• Except in very specialized cases, cryogenic valves have room temperature actuators

• Valves can be manually operated or more commonly operated via a control system. The actuators for remote operation are typically electro pneumatic – a current or voltage signal from the control system regulates the pressure on the pneumatic drive that controls the valve position.

• A wide range of cryogenic valves is available in industryJune 2019 Lecture 17 Cryogenic Equipment Slide 21

Basic Valve Types(All can be implemented in cryogenic systems with proper design and materials)

June 2019 Lecture 17 Cryogenic Equipment Slide 22

Globe Gate

Ball

Butterfly

CheckRelief

Examples of Cryogenic Valves

June 2019 Lecture 17 Cryogenic Equipment Slide 23

JT Valve

Cryocomp

½ inch IPS

Designed to be installed inside cryostats

Heat Leak to 4.2 K is ~ 1 W

CVI

Model 2060

Contains

vacuum jacket

Heat Leak reduced

via thin walled tubes

1 inch valve has a

measured heat leak of

1.3 W to 4.2 K

Sizing of Valves

• Valves are typically sized using the parameter Cv

– This parameter is defined as the number of Gal/min of water that passes through the valve with a pressure drop of 1 psi

– This can be related to properties we care about in cryogenics by

– Be sure to use appropriate properties

– Note oR = (9/5)K

June 2019 Lecture 17 Cryogenic Equipment Slide 24

From Acme

Cryogenics

Catalog